Control of Microdochium albescens in pre-germinated and dryland rice seeds

ABSTRACT: The fungus Microdochium albescens can interfere in the germination of seeds and in the death of rice seedlings; however, there is not technical indication for its control by seed treatment. This research evaluated the efficiency of fungicides in the treatment of pre-germinated and dryland rice seeds in the control of M. albescens. Seeds of the cultivars, Epagri 109, SCS116 Satoru, SCS121 CL and SCS122 Miura were treated with the following fungicides (g a.i./100 kg of seeds): fluazinam + thiophanate methyl (9.45 + 63), pyraclostrobin + thiophanate methyl (5 + 45), carboxin + thiram (60 + 60), metalaxyl-M + thiabendazole + fludioxonil (3 + 22.5 + 3.75), carbendazim + thiram (45 + 105), carbendazim (45). Seeds without fungicide treatment constituted the control. The treated seeds were sown in potato-sucrose-agar (PSA) culture medium and incubated at 25 ± 2 °C and photoperiod of 12 hours for 14 days. Treated seeds were also submitted to the germination test. Fluazinam + thiophanate methyl and metalaxyl-M + thiabendazole + fludioxonil showed greater control of M. albescens, not differing statistically between them, in the five cultivars and in the two cultivation systems. The tested fungicides provided seed germination above 90% in the four cultivars.

THE BIOLOGICAL PECULIARITIES OF PRODUCER STRAIN OF MICROBIOPREPARATION 11-1 BACILLUS SP. – THE ANATAGONIST OF SUNFLOWER PHOMA ROT PATHOGEN

We studied the cultural and physiological characteristics of the producer strain 11-1 Bacillus sp. – the antagonist of sunflower Phoma rot pathogen to develop the technological regulations for the production of a microbiological preparation in a «wettable powder» form. We studied the cultural characteristics of the producer strain on three agar media: potato sucrose agar (PSA), Czapek’s agar and Tylon-3; the characteristics varied significantly depending on the nutrient medium. The maximum diameter of colonies on the tenth day of incubation developed on the Tylon-3 medium – 66×99 mm. We established the optimal conditions for the cultivation of the strain on liquid nutrient media: temperature – 30–35 °С, medium pH from 6 to 10. We found that molasses is an optimal source of carbon nutrition, while peptone is the most favorable source of nitrogen nutrition. We established that the Tylon-3 medium is the optimal complex liquid nutrient medium for the cultivation of the bacterial strain 11-1 Bacillus sp.

Application of the Best Techniques to Reduce the Percentage of Storage Fungi in Peanut Seeds Arachis hypogaea

This study was conducted during the season 2019-2020 with the aim of testing the efficiency of some techniques to eliminate or reduce the frequency of storage fungi, namely Aspergillus flavus, A. niger, and Penicillium italicum naturally contaminating peanuts seeds. The seed sample was treated by soaking in hot water (50˚c, 60˚c, 70˚c), soaking in salt water at concentrations 10%, 15%, 20%, roasting in an ordinary oven at 150˚c for 10, 20 and 30 min, and roasting in a microwave oven at 100˚c for 1, 3, 5 and 7 min. The frequency of fungi occurrence percentage was estimated in seeds after treatments and incubation on the nutrient medium Potato Sucrose Agar (PSA). The results indicated the efficiency of all the techniques used in reducing the frequency of fungi in the treated seeds, as the fungus P. italicum was the most sensitive fungus under all techniques, and the study proved the superiority of the treatment by microwave roasting over the rest of the techniques, as it eliminated all the fungi carried in the seed by 100% when the duration of time used is 5 minutes.

Physiological Studies of Myrothecium Roridum: An Inciting Agent of Myrothecium Leaf Blight in Cotton

Background: Cotton is one of the most important cash crops in India. It is also called as “White gold” because of its agricultural as well as industrial importance. Myrothecium leaf blight is an emerging disease in cotton which is growing consistently throughout the country and has been reported to cause significant losses in major cotton growing tracts of odisha. Considering the importance of the disease, the present investigation has been taken up to study the physiology of the fungus. Methods: An experiment was conducted in-vitro during 2016-18 to investigate the effect of temperature and pH on the growth of M. roridum. Seven different nutrient media viz. Potato Dextrose Agar (PDA) medium, Potato Sucrose Agar (PSA) medium, Host Leaf Extract Agar (HEA) medium, Potato Carrot Agar (PCA) medium, Czapek’sdox Agar (ZA) medium, Richard’s Agar (RA) medium and Oat meal agar medium (OMA) were tested under in-vitro conditions to ascertain a suitable medium for the growth of M. roridum. Result: The investigation in laboratory conditions has revealed that out of seven nutrient media tested, maximum radial growth was recorded in Potato Sucrose Agar (PSA) with an average radial growth of diameter 76.06 mm and the least growth was recorded on Richard’s Agar with a diameter of 23.66 mm. The growth of the fungus was observed to be maximum at a temperature of 28oC with a diameter of 61.09 mm and the minimum average growth of 17.36 mm was recorded at 36oC. Studies on pH revealed that that the fungus grows well in neutral and slight alkaline medium (6.5 - 8.0).

Fungi on irrigated rice seeds produced in the pre-germinated system in the Alto Vale do Itajaí region, Santa Catarina state, Brazil

ABSTRACT: The aim of this research was to identify and quantify fungi infecting irrigated rice seeds produced in the 2015/16, 2016/17 and 2017/18 harvests in the pre-germinated system in the Alto Vale do Itajaí Region, Santa Catarina State, Brazil. A total of 479 lots of eight cultivars were analyzed. Seeds were disinfected and sown in potato-sucrose-agar culture medium with incubation for seven days at 25ºC ± 2ºC and photoperiod of 12 hours. The main fungus detected in the three crops season was Microdochium albescens with 54.9% of average incidence, followed by Alternaria padwikii (7.7%) and Bipolaris oryzae (3.3%).

Transmission of Microdochium albescens from seeds to seedlings in the pre-germinated cultivation system of irrigated rice

ABSTRACT: The fungus Microdochium albescens is one of the main pathogens associated with irrigated rice seeds in southern Brazil. The objective of the present study was to quantify the transmission of M. albescens from naturally infected seeds to the crown, coleoptile, and first true leaf of the seedlings of six cultivars growing in pre-germinated cultivation system of irrigated rice. Seeding was carried out on a water-saturated substrate, using four untreated seed lots for each of the six cultivars. At 14 days after sowing, the crown, coleoptile, and first true leaf of the seedlings were carefully highlighted, and the samples were disinfected and plated onto potato-sucrose-agar culture medium. M. albescens was transmitted asymptomatically to crown, coleoptile, and first true leaf, at rates of 39.3%, 25.8%, and 5.4%, respectively (these values represent the average incidence of the six cultivars). This is the first report that proves that M. albescens is transmitted from infected seeds to irrigated rice seedlings in a pre-germinated seed system.

تعريف مُسبب مرض العفن السُخامي على الأشجار في محيط جامعة عمر المختار – البيضاء -ليبيا

أُجريت الدراسة خلال الموسم 2017-2018 بهدف تعريف مُسبب مرض العفن السُخامي على أوراق بعض النباتات في محيط الجامعة شملت التين، الزيتون والدفلة، اللوز، الخروب، الكافور، الإكليل، الصبار النجمي، الورد البلدي، البزرومية ونباتات أخرى، حيث جرت زيارات أسبوعية لجمع العينات الورقية، وفحصها لمُلاحظة وجود المرض والحشرات المُرافقة، كما تم عزل مُسبب المرض على الوسط الغذائي آجار البطاطس والسكروز Potato sucrose Agar (PSA)، وتعريفه بناءً على صفاته المزرعية، والشكلية، واختبار قُدرته على إصابة النسيج النباتي. أثبتت الدراسة وجود المرض على أشجار الزيتون والتين والدفلة مرافقاً لوجود الحشرات الماصة، في حين خلت بقية النباتات من الإصابة عدا الصبار النجمي، وبعض الحشائش. كانت أعلى نسبة وشدة إصابة بالمرض (75.5% و69%) سُجلت على أشجار الزيتون يليها الدفلة ثم التين. نتائج العزل أثبتت تسجيل الفطر Alternaria alternata على الأوراق، فيما برهنت نتائج اختبار القدرة على إصابة نسيج النبات عدم ظهور أي أعراض مرضية على الأوراق المعداة اصطناعياً.

Development of rice conidiation media for Ustilaginoidea virens

Rice false smut, caused by the ascomycete Ustilaginoidea virens, is a serious disease of rice worldwide. Conidia are very important infectious propagules of U. virens, but the ability of pathogenic isolates to produce conidia frequently decreases in culture, which influences pathogenicity testing. Here, we developed tissue media with rice leaves or panicles that stimulate conidiation of U. virens. Generally, rice leaf media more effectively increased conidiation than panicle media, and certain non-filtered tissue media were better than their filtered counterparts. Among the tested media, the Indica rice leaf medium with 0.06 g/ml of Wanxian 98 leaf was most efficient for inducing conidiation, and it was also usable for conidiation-defective isolates. Although the conidia induced in rice tissue media were smaller, they were able to germinate on potato sucrose agar medium and infect rice normally. This method provides a foundation for the production of conidia in U. virens that will be widely applied in the pathogenicity testing as well as in genetic analyses for false smut resistance in rice cultivars.

Inoculum production and evaluation of temperature and leaf wetness for Passalora sojina inoculation in soybean

ABSTRACT The objective of this study was to develop a methodology for inoculum production and inoculation of Passalora sojina in soybean to assess the reaction to frogeye leaf spot. Thus, sporulation of fungal races was quantified in five substrates under two light regimes. The temperature and the leaf wetness period that resulted in greater infection efficiency were also determined. Petri dishes containing the culture media Oat Flour Agar (OFA), Tomato Juice (FTJ), V8 agar juice (V8), Infant Food (IF) and Potato Sucrose Agar (PSA) plus isolates of P. sojina races 23, 24 and 25 were subjected to 12-h photoperiod and 24-h continuous dark. Inoculated plants were incubated at temperatures of 15, 20, 25, 30 and 35 ºC and leaf wetness periods of 12, 24, 36, 48 and 72 hours. Experimental design was completely randomized with five replicates. There was interaction among isolate, culture medium and photoperiod. The highest sporulation (conidia/cm2) was obtained in the culture media FTJ (race 23) and V8 (races 24 and 25) under 12-h photoperiod. The optimum temperature for the disease development was 27oC under 72 hours of continuous leaf wetness.

PENGARUH TINGKAT KONSENTRASI FRAKSI EKSTRAK DAUN MENGKUDU DAN MIMBA TERHADAP PERTUMBUHAN DAN SPORULASI Colletotrichum capsici

Salah satu penyakit utama yang menyerang tanaman cabai adalah penyakit antraknosa yang disebabkan oleh Colletotrichum capsici. Penelitian ini bertujuan untuk mengetahui tingkat keefektifan fraksi ekstrak daun mengkudu dan fraksi ekstrak daun mimba serta mempelajari pengaruh tingkat konsentrasi fraksi ekstrak daun mengkudu dan fraksi ekstrak daun mimba dalam menekan pertumbuhan dan sporulasi jamur C. capsici secara in vitro. Penelitian ini dilakukan di Laboratorium Ilmu Penyakit Tumbuhan Fakultas Pertanian Universitas Lampung pada bulan April 2015 sampai Juli 2015. Alat yang digunakan antara lain alat fraksinasi sederhana, mikropipet, haemocytometer, dan Laminar air flow. Bahan yang digunakan antara lain daun mengkudu, daun mimba, biakan C. capsici, dan media Potato Sucrose Agar (PSA). Penelitian ini menggunakan rancangan acak lengkap (RAL) tersarang dengan dua faktor dan data dianalisis ragam kemudian dilanjutkan dengan perbandingan polinomial ortogonal pada taraf 1%. Hasil penelitian menunjukkan bahwa fraksi ekstrak daun mengkudu dan fraksi ekstrak daun mimba memiliki keefektifan yang tidak berbeda dalam menghambat pertumbuhan dan sporulasi C. capsici secara in vitro. Tingkat konsentrasikedua jenis fraksi ekstrak tanaman tersebut berbeda dalam menghambat pertumbuhan dan sporulasi C. capsici. Semakin tinggi tingkat konsentrasi fraksi ekstrak tanaman uji tidak selalu diikuti dengan meningkatnya daya hambat terhadap pertumbuhan diameter koloni C. capsici, tetapi semakin tinggi tingkat konsentrasi fraksi ekstrak tanaman tersebut semakin efektif untuk menghambat sporulasi C. capsici.